The VideoLAN Forums

Hi,

I have a sort of weird problem or perhaps just a question. I use an onboard sound card(Realtek) where I can set output to

headphone
2ch speaker
4ch speaker
6ch speaker
8ch speaker
dolby digital 5.1
digital pcm

Now when I put it on dolby digital 5.1 and in VLC A/52 over S/PDIF I get stuttering sound. However if I use dolby digital 5.1 and in VLC 5.1 I get no stuttering. I also hear sound in my surround speakers. How can I know if this is real dolby digital and not some sort of dolby surround?

You might just be able to fix spdif by changing your audio output module to Win32 waveout extension output. Other people have found that Directx audio and spdif don't mix.

thx for the suggestion but it didnt work.

However if I use dolby digital 5.1 and in VLC 5.1 I get no stuttering.

That is because VLC does DD -> 5.1 decoding then your soundcard (or drivers of soundcard to be precise) does 5.1 -> DD encoding. There is unneeded encoding part that causes quality loss, but if you can sleep during night, it is okay =) VLC SPDIF output has some issues.

S/PDIF is a pass through it's just split from the input and passed to the output there should be no decoding or encoding going on here. The output issue with DirectX is purely a timing issue thus causing a stutter effect. The only decoding going on here should be by the receiver the S/PDIF cable is attached to.

DJ, optimal solution no encoding is but for the time being satisfied with an extra encoding I have to be.

I've got a similar problem. Is there any way to make VLC *not* decode the digital audio? I want it to pass the digital signal out to my receiver. I've got S/PDIF selected, but VLC decodes it anyway. If I set my receiver to optical input it only gets a stereo signal, if I set it to six channel direct, it gets full surround. Any ideas?

For me the win32 waveout trick also doesn't help. SPDIF output is always stuttering beyond recognition, although it works peferctly in WinDVD4 and WMP10. So there must something werid be happening to the digital channel. Maybe VLC doesn't decode it, but somehow doesn't allow it to play as one continuous stream. Maybe it's really a "timing-issue" as it was posted in several threads, but this issue is not restricted to DirectX, it also occurs with waveout.

How is your setup?

Do you have an external surround receiver hooked up to your computer with a digital or optical cable? Or is it an analogue connection with a cable for each channel?

If you have an analogue connection, the digital sound (A/52 SPDIF output) might be played "as is" without being decoded to proper sound. That (in my analogue desktop surround speakers) sounds like stuttering noise. But my digital receiver hooked up with a SPDIF cable, decodes the stream to perfect DD5.1...

It works in WMP10 and WinDVD4, because they maybe don't use SPDIF...

Direct Show does NOT natively support S/PDIF or ac3 for that matter. It takes third party support to do this and an additional setup for what ever codec you install.

In any event VLC is NOT a Direct Show player and as such these codecs will not effect VLC.

one more thing to check... when you switch to wave32 out, make sure you completely restart VLC. A lot of the audio changes take place instantly, but not that one.

I'm having the very same issue here.

When I set the audio device in VLC to "A/52 over S/PDIF" all I get out of my speakers is some stuttering sound. If I play the very same mkv file in Windows Media Player I get proper 5.1 DD sound (using AC3filter S/PDIF passthrough).

The stuttering sounds like the receiver decodes half a second of audio, than repeats that piece for three seconds than decodes the next half second. So you can identify the stuttering as being the sound that is supposed to play.

When I switch the output device back to Stereo the receiver will switch back to PLII Music. So the receiver is getting the format switch from DolbyDigital to PCM Stereo and vice versa. It's just not decoding DD5.1 properly.

I tried several audio output modules but ended up reverting it back to default since none of them seems to have a healing effect. Though I can say for sure that when audio output is set to Win32 waveOut instead of default, the stuttering pieces are about twice as long as before. So instead of half a second I maybe get one second of decoded audio that than repeats itself for another three seconds.

The Soundcard is an onboard Realtek Card on a ASUS P5WD2 Premium, which also supports DolbyDigital Live. So of course if I switch the Digital Out default Format from 48kHz Stereo PCM to Dolby Digital Live 5.1 in the Windows Control Panel and set the audio device in VLC to 5.1 instead of A/52 over S/PDIF I will get 5.1 sourround sound out of my speakers. But this is a less than optimal solution as VLC is decoding the AC3 stream to 5.1, hands it over to the system which than does DDL5.1 encoding to the 5.1 channels and sends it over to the receiver who again decodes the channels. That's a bit like mp3->wav->mp3->wav de/encoding, and we all know nothing good can come out of this quality wise

Since DolbyDigital and DTS passthrough works in a variety of apps (AC3filter - thus WMP, PowerDVD, WInDVD) on my system I'm blaming VLC right now for the broken Sound.

The System is running VLC 0.8.6c on Vista Ultimate x64 on the MB mentioned above. The receiver is a Onkyo TX-SR505E supporting Dolby Digital, DTS and PCM of course at sample rates of 44.1, 48 and 96 kHz (these are also the Options that I have activated in the Supported Formats tab of the Digital Output Properties in Windows Control Panel). My default output format is 48kHz PCM Stereo.

I have the exact same problem, Everything is working great except for DTS and DD (AC3) soundtracks. I get the VLC-stuttering. I really want to get rid of it since the 5.1 Decode - 5.1 Encode - Reciever decode process is introducing alot of background noice, especially to my sourrond speakers. I am also experiencing a certain loss of bass during this "round-about" coding..

Isn't there anyone with a solution out there, I really want this to work since im addicted to VLC

i have the exact same problem, using soundblaster x-fi fatal1ty connected to a yamaha reciever via a coaxial cable on vista 32bit, tried the wave32 out module.

I set the output to win32 and the output frequency to 44100 and achieved decent results. Still, I think I can hear some sound quality issues, but it is managable. I truly hope the next version of VLC will fix this big bug - so many people have it!

Most if not all of the problems come from DirectX and it having some timing issues, this is completely unrelated to VLC though.

Switching to Win32 Wave Out does not solve the problem...it just makes the stutter a little slower. The little blue light indicating a digital signal just blinks off and on with each stutter. sigh.

Very frustrating...Realtek updated their Vista drivers a few days ago but updating solves nothing.

I have the same problem coming out of my abit IP35 Pro mobo with the realtek hd audio. It passes through from DVD fine, but if I try to play an mkv or .iso image through vlc you get the maddening stuttering.

Using Vista Ultimate, going into a Sony amp. It is, incidentally, NOT a 7.1 amp, but I don't think these mkv and iso files actually contain 7.1 audio yet, so hopefully thats not the problem.

I can't believe nobody has figured this out yet. Any videolan moderators or tech wizards know out there kow how to fix this? My new HTPC is all set up and looking amazing, but for this ONE...THING...

So I guess here are my questions...

1. Is vlc SUPPOSED to play ac3 audio through spdif? If not, can someone recommend a player that will?
2. If so, does ANYBODY have this working right using vlc as a standalone...no other ffdshow or ac3filter running?
3. If you DO need ac3 filter or ffdshow, can you point me to some detailed settings that will make this work right?
4. I have two audio output drivers...Realtek HD Audio and Realtek HDMI HD Audio. I am using the HDMI straight into the TV for audio, and trying to use the spdif (optical) for audio, since my receiver has no hdmi inputs. The video card also has a component output and the problems are the same using it as using the HDMI. Question...I shouldn't be using the HDMI driver since I'm only using the HDMI for video, right?

I think I answered my own question.

VLC is broken and it sounds like there are no plans to fix it.

I loaded up Media Player Classic and ffdshow and after a few tweaks, I am finally playing 5.1 DD through my spdif, the steady blue light on my receiver indicating a perfect stutter-free signal.

I think the picture is better in VLC and the features and flexibility are MUCH better, so I really hope they fix this problem in the future. Plus I have in vested hours setting up the Hotkeys, programming my ATI remote to use them, setting up an overlay for my keyboard....all wasted hours, plus I have to trade a great program for an "okay" one.

Word to your mama, VLC men...you are gonna run into hundreds of guys next year who just want to run HD Audio through Windows Vista through spdif into their receivers. IT SHOULDN'T BE THIS HARD and you will see another fifty pathetic posts from frustrated guys who can't believe this incredible player won't play digital audio through their systems.

NOBODY has an answer, nobody has posted a working workaround. Its just broken. Fix it, please please please.

I am not gonna be rude, but I don't know why.

If you really care about SPDIF, then fix it! If you don't know how to fix it, then give a developer some SPDIF material in order to have that tested. If you don't have that, then give him the money to do so...
You have to understand that we do that on our free time, and we have now NO developer full time on Windows, moreover testing all the different configurations and broken drivers on SPDIF.

With the Realteck drivers try downgrading older drivers instead, this has worked for some. If you still get the stuttering problem then try disabling the audio track 1 (Menu bar -> Audio -> Audio Track...) and re-enabling it and see if the audio comes in clear.

Edit! Woe! What I wrote earlier was really confusing. Ok fixed now.

Hi,

I had this exact problem & registered here to try & find a solution. I am using an external USB Soundblaster Live unit & taking a digital optical feed to a Denon receiver. I changed to Win32 Waveout & it has solved my problems . Thanks very much.

Martin

I use version 0.8.2 for most of my dvds and vids, and use sdf setting. With some of the newer and larger video files I've downloaded, this version doesnt work. I use the newer version for these files and use the 5.1 setting but I think the sound quality and channel seperation is much better in dolby digital.
I'm no expert, but if the old version works and the new version does not, the probem is with the player and not the sound card.
i first noticed the problem with version 0.8.4a. i just downloaded the newer version and still have the problem. This is the only video player I use. I think it's the easiest and most stable player out there so I really hope they fix this on the next version.

Nice try guy but SP2 & DirectX 9c in Oct of 04 came along. Microsoft recommended to update your sound and video drivers after the update and this has solved the issue for most people. VLC updated the DirectX section in Version 0.8.4 to be more compatible with DirectX 9c. Also be aware that most quality players relinquish DirectX when S/PDIF is used. Using DirectX, just does not have good timing when sync is employed. VLC must have sync as it was designed as a packet based streaming media player.

The Realtec AC97 drivers are known to have issues. Try searching this forum for other users that have found drivers that work.

I have The Realtec AC97 drivers to and it works fine

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Hi All,

Very happay (and sad) to report exactly the same problem with stuttering AC3 DD5.1 sound over SPDIF. My Denon receiver goes banana when VLC plays DD5.1 movies. No such problem with PDVD7, Zoom Player, Media Player, et al.

Changing output module does nada.

Is the development team aware? How do I report the bug?

BR / Bo